Ovitraps have been widely used for many years to collect the eggs of container-breeding mosquitoes (Service, M. W. (1976); In Mosquito Ecology, John Wiley Inc., New York, pp. 1-42). The CDC Gravid Mosquito Trap is the only published trap for gravid adults, but collects ovipositing Culex mosquitoes and operates on a different principle (see Reiter (1983), Mosquito News 43 (4): pp. 496-498; and Reiter (1987), Journal of the American Mosquito Control Association 3(2): pp. 325-327).
The problem is to collect live, adult Aedes aegypti, Aedes albopictus, and certain other Aedes mosquitoes. Aedes aegypti is the principal urban vector of dengue, dengue hemorrhagic fever and yellow fever throughout the tropics. The Yellow Fever Mosquito Aedes aegypti is an urbanized species which breeds in or close to human habitation and is the principal urban vector of dengue and yellow fever. In recent years, a massive resurgence of Aedes aegypti has resulted in millions of cases of dengue in the Americas, including some in the United States. An effective, efficient device for collecting live Aedes aegypti therefore is urgently needed for surveillance and monitoring of vector populations, for virus collections, and for the evaluation of control methods during epidemics.
Aedes albopictus also considered an important vector of dengue. It is an Asian species which recently invaded the United States in used tire shipments and is now common in at least 20 states. Apart for its significance as a vector, it has become a severe nuisance in many cities, such as Houston, New Orleans and Memphis. Aedes triseriatus is a common North American species and is the vector of LaCrosse encephalitis. All three species originally bred in tree-holes and other natural cavities, but Aedes aegypti (and to a certain extent Aedes albopictus and Aedes triseriatus) have adopted artificial containers in the domestic environment as their principal oviposition site.
At present, Aedes aegypti populations are assessed by highly subjective methods, such as counts of larva-infested sites or aspirator collections inside houses. These are so dependent on the diligence and skill of the field personnel that it is difficult to regard data as quantitative. The prior art includes a number of automated traps using a constant air flow, such as the CDC Gravid Mosquito Trap discussed above. Certain mosquitoes, however, including Aedes aegypti, will not fly into strong air currents. This is particularly true when seeking sites for oviposition. Consequently, the constant air flow type traps have proven ineffective for collecting gravid mosquitoes of such species.
One object of the invention therefore is to automatically collect live, adult, gravid Aedes aegypti mosquitoes. A non-subjective, automated method for collecting the adult mosquito would be of great value for surveillance, evaluation of control operation and many research purposes, but has never been devised. The invention seeks to provide such a method by trapping the mosquitoes as they settle to lay their eggs. In addition, it will probably be suitable for collecting other important vector species such as the Asian Tiger Mosquito Aedes albopictus and the Eastern Treehole Mosquito Aedes triseriatus.
As a further object, the collection device should not produce any substantial air flow or turbulence prior to collection since such air currents deter certain insects from entering the trap.